Felted sheet and process of making same



Aug. 20, 1929. KIRSCHBRAUN FELTED SHEET AND PROCESS OF MAKING SAME 'Filed April 20. 1921 H J/m f a v Patented mg. 20, 1929.

UNITED STATES 1,725,647 PATENT OFFICE.

LESTER KIRSGHIBRAUN,

or CHICAGO, ILLINOIS,

FELTED- SHEET AND PROCESS OF MAKING SAME.

Application filed April 20,

, formed with theinner plies or body of the sheet having a substantial amount of bituminous binder incorporated therewith during the felting or paper making operation; to provide a sheet or product Whose strength is .materially improvedby the incorporation of this waterproof or pitchy binder and one which may be subjected to further saturation by passing it through a body of saturating substance; to provide a product whose central body plies consist of felted fibrous material impregnated with an asphaltic or bi-' tuminousbinder and whose outer plies com prise relatively thin layers or plies of fibrous stock devoid of any binder substance; the outer plies being integrally united with the impregnated inner plies during the initial paper making operation to provide a product which is capable of speed tank saturation due to its strength and also to the thinness of the portions which necessitate subsequent satur ation; to provide a product which after the initial formation is water-resistant and does not tend, upon storage, to absorb excessive moisture which tends to retard subsequent saturation; to provide a product whose plies upon being subsequently passed through the saturating tank do not tend to separate or pull apart and one in which, due to the binder substance incorporated in the central plies unites the plies into a unitary sheet; to provide a product whose structureis better felted due to the superior formation of the multi-cylinder apparatus whereby a better strength may be obtained by the use of an inferior paper stock and one in which a stock not commonly adapted to tank saturation may be readily impregnated to provide a process for producing this product and in general to provide an improved process and product of the character referred to. v

Fig. 1 is a diagrammatic side elevational view of an apparatus which may be used to produce the multi-ply product.

Fig. 2 is a fragmentary perspective view showing a detail of the multi-ply sheet.

Referring more in detail to the drawings, the paper stock used to make the separate plies 1921. Serial No. 463,031.

may be introduced from suitable beaters through the pipes 1 and 2 into the vats 3 and4, which it is to be noted in the present instance, are illustrated as being the vats in which the outer plies are formed and which contain no emulsion.

Describingnow-the manner in which the adhesive substance may be introduced, an emulsion made, for instance, as described in detail in my United States Patent No. 1,302,810, may be mixed with fibrous stock in any suitable mixing apparatus and the entire mixture introduced through the pipes 5 and 6- to the vats] and 8, respectively. a

With stock 'nthe central vats 7 and 8 containing the waterproofing substance, and the end-vats 3 and 4 devoid of any waterproofing material, the blanket 9 driven by any suitable source of power (not shown) and passing over the guide rolls 10, 11 and 12, there is released from the initial cylinder mold 13 in vat 4 the first ply of the sheet. In a like manner subsequent plies are taken 0d of the cylinder molds 14, 15 and 16, mounted respectively in vats 8,7 and 3. The usual couch rolls 17 may be positioned above the respective cylinder molds, serving to hold the blanket against the mold. The sheet thus formed Will have the two outer plies formed of a plain web of paper stock, while the inner plies contain the waterproofing material in emulsified form intinately incorporated with the fibers of the we This multi-ply' sheet is carried by the blanket 9 over the guide rolls'18 and thence through the usual pressing rolls 19, after which the blanket is returned to. again receive the plies, pressed being led to drying rolls (not shown) The upper blanket 20 may be returned over,

the multi-ply sheet after being guide rolls and stretcher rolls 2 1 by means of which a regulated tension may be maintained upon the blanket; a

It is understood, of course, that the emulsion may be supplied to all of the vats, or that the plies containing the waterproofing'substance may be arranged in any manner described other than that shown in the draware devoid of water-' to heat the sheet in order to cause the waterproofing substance to more thoroughly fuse with the fibres, spreading and coalescing with the plies to form a continuous waterproofing medium.

Heretofore roofing felts and fibrous sheets for tank saturation have been formed and produced upon asingle cylinder machine for tank the reason that suclrsheets, if produced in plies upon a multi-cylinder machine, have a decided tendency, when subjected to asphalt saturation, to come apart. On this account, the use of a single cylinder machine in the formation of relatively thick felted sheets as for example, has limited the character of the stock which could be used to such a degree of freeness as would permit the building up of the desired thickness onone cylinder. As will be appreciated by those familiar with the art, the formation of such a stock on a single cylinder machine necessarily results in a sheet which is relatively rough and in which the full strength of the fibres cannot be completely developed. On this account, stocks which are used for the purpose of making froofi ng or flooring felts have been limited largely to rags in combination with various rag fibres and minor percentages of cheaper stocks.

process of the present invention, it

'3 By the found possible through incorpohas been rating predetermined amounts of asphalt or and production in the bituminous binder in emulsified form into the sheet to produce a product in which the plies are so firmlyarranged and the moisture content of the inner plies so reduced that the tend ency to separation of the plies in the hot saturating bath is entirely eliminated. This has made it possible to utilize the multi-cylinder machine for the purpose of producing roofing and flooring felts by tank saturation in the manner which will be hereinafter described. In addition, the use of the multic'ylinder machine makes it possible to use the stocks which have heretofore been incapable of use upon the single cylinder machine and to produce felted sheets of such a quality and of such a character as to permit of substantial economies in the stock used and rapid saturation subsequent tank saturating operation. I The essence of this invention consists in introducing and mixing with the stock used in the inner cylinders of the multi-cylinder machine, asphalt binder in the form of a nonadhesive emulsion with water and clay which has the effect of presaturatingthese inner plies and integrally and firmly uniting them to the outer plies leaving the relatively thin surface to be saturated in thesubsequent operation. l

The papermachineused for this purpose is the well known multi-cylinder machine of to .075 of an inch in thickness as box board, chipboard and various fibrous container boards known to the art. For the purpose of the present invention, the multicylinder machine should comprise at least three forming'cylinders and preferably five to seven cylinders may be employed to better advantage. I

The asphalt used may be any of the commercial varieties such as natural asphalt or the residual 1 )roduct-from petroleum reduced to a solid or semi-solid form; or the binder, instead of being, of an asphaltic nature may beof pitchycharacter such as coal tar or water gas pitch. vegetable and-animal pitches and-analogous fusible waterproofing pitches, whether strictly of a bituminous nature or not. These waterproofing pitches have a melting point of say, upwards of 100 degrees F., and while being of a more or less solid character, have properties of slowly flowing at normal temperatures and of being adhesive when contacted with other substances. In. order to use the pitches or bituminous materials described, it is necessary to convert them to a non-adhesive state, which is accomplished by a process of emulsification whereby the pitches in hot liquid condition are emulsified An'exceedingly fine degree of-dispersion is, required in order to convert the pitches 'de scribed intothe non-adhesive form and it is also essential that the colloidal clay present be so adsorbed on the particles and retained ,as to provide a protective element against coalescence'under the pressure of contact surfaces such as blankets, wires, etc., on the paper machine. The degree-of dispersion necessary will vary from that approaching colloidal particles in size to an emulsion so constituted that only'about 1% of the particles will be retained on a screen having 40,000 openings per square inch. tical operation, all of the emulsion in liquid form is screened through 40 or 60 mesh screen, the small amount retained being rejected as unemulsified, in comminuted form, and incapable of use on the machine without adhering to the parts thereof.

The bituminous emulsion so/produced is thinned with water to a consistency'by which it can be handled readily by pumps and may .be mixed with fibrous beater engines or at the mix box prior to reaching the screens of the multi-cylinder In prac stocks either in the machine. Where separate systems are available for liner and filler, it is preferable to mix the asphalt with the fibrous stock in the heaters but where a single system only is available, it is necessary to'mix the asphalt at the screens as described. The asphalt emulsion when mixed with the fibrous stock is preferably fixed, which is accomplished by the ad ition of silicate of soda to the mixture in the heaters followed by treatment with alum; or if set outside of the heaters, the emulsion itself is treated with silicate of soda and alum prior to its mixture with the fibrous stock. These fixing agents have the property of causing the dispersed asphalt to seek contact with the fibrous stock and be advantageously carried thereby and lessen the tendency to pass through the sheet or adhere to the parts of the machine. I The formation of the sheet and the manipulation of the stock on the machine is carried out in the usual manner without any interference whatsoever-with the customary procedure of making the paper. The asphalt is preferably incorporated into the stock which forms all of the inner plies, leaving a relatively thin outer ly on both sides of the sheet devoid of the ituminous material. For example, on a five-cylinder machine, a 50- point felt may be made which will carry .014 on each of the three inner cylinders and .004: onthe remaining two outer cylinders. A

Upon reaching the driers, the wet web is .s' ilbjected to a temperature above the melting point of the asphalt or bituminous material, and with the removal 'of the water, the dispersed asphalt gradually coale'sces, in effect coating the flowing through the inner plies, fibresthereof, and firmly uniting them together and adhesively binding the inner plies with the outer plies without actually saturating through the outer plies. The amount of asp alt used can be varied, depending on the result to be achieved and the character of the stock to be used. For example, if it is merely desired to cement the plies together .so as to preclude separation in the tank,.a relatively small amount of asphalt will serve this purpose such as 20%. 'However, on the other hand, where in addition to maintaining the plies, it is desired to accelerate tank saturation, the amount of asphalt to be incorporated should be suitably in excess and preferably should reach 100% or more in relation to the fibrous stock. Likewise, where the fibrous stock is of a refractory character to tank saturation, it is desirable to incorporate the maximum amount of asphalt so that the tank saturating operation may be facilitated to the greatest possible extent.

Stocks used for this purpose can be varied to produce a sheet comprising all rags, but preferably a large content of. cheap stock such as news or mixed papers can be incorporated and yet produce a sheet which is capableof rapid tank saturation. As is well known, the use of relatively hard stock tends to reduce strength and the addition of the alt likewise has a substantial .eifect in strengthening the sheet, this strengthening generally resulting in an increment of about w ewe w "uct ma I have found that a mixture of 50% rags and 50% of.mixed papers makes a very desirable sheet, say, for a 40 to '50 caliper product, the

resulting sheet having flexibility, strength and drag in the fibres. For thinner sheets, a stock comprising of news and 20% rags serves excellently to produce a desirable product for subsequent saturation where the inner lies tent explained above. In certain cases, norags at all are needed and the entire furnish may be composed of the cheap paper stocks, the characterof the sheet being such that the resulting tank sufficient ease and results in the sheet having the desired flexibility and otherqualities required for high grade roofing products.

It will also be understood that where the machine is equipped with separate systems so that various stocks can be used on liner and filler, the inner plies may advantageously be composed of all paper, presaturated and the outer plies may carry either a strengthsaturation takes place withgiving stock such as kraft or long fibre" stock such as rags, which gives the desired flexibility, drag and tank saturating properties.

It will be understood in connection with this subsequent saturation that the rapidity with which this operation can be carried out,

moisture as a retardent of saturation is well known to those skilled in the art, it being understood that the dry roofing felt of commerce ac uires between 5% to 10% of moisture,

which moisture must be converted into steam and driven from the sheet prior to the en trance of the hot asphalt into the sheet. It is estimated that practically two thirds of the distance travelled by the sheet in the saturating tank is occupied, by a removalof the moisture prior to the entry of the asphalt, and to of the sheet which enables it to' this extent, the retardation of the saturation is affected by the moisture.

An interesting characteristic of this prodfurther be noted in that it is practically impossible to separate the, various plies after the sheet is. dry. As is well known to those familiar with the product .of multicylinder machines, a more or less distinct division can be noted acter which makes it 1 ossible by tearing the sheet to distln uish t eseparate webs, particularly if t esej be slightly moistened. This characteristic-is absent in the product of the resent invention, a patently through the additional bondin" e ect upon its coalescence. his may be influenced by the slight infiltration of the asphalt when in products ofthis charof the asphalt .carried out in which the product, instead of tent of the entire sheet.

the wet plies containing asphalt areunited with those free from asphalt as they pass under the couch rolls. This results in a sheet in which the lies cannot be pulled apart even when wet an the only way in which the thickness of the inner plies can be determined is by wetting the outer plies and actually abrading away the unsaturated stock until the resistance of the inner and saturated portions precludes further separation.

An-illustrative run of this process is as follows: Mexican asphalt of about 150 melting point was converted into non-adhesive form by the emulsifying operation outlined above, the proportion of asphalt to clay. be ing about four to one. "To the emulsion thus produced was added silicate of soda andaluminum sulphate to the extent of 2% of the former and 5% of the latter. The stock used throughout the sheet was the same and com-- prise 50% of mixed papers, 25% of dark cottons and 25% of tailors muss: This stock Was beaten up in the presenceof of 1% of caustic soda which was subsequently neutralized'with 2% aluminum sulphate. The

sheet was formed on a multi-cylinder machine. in the usual manner, the asphalt beiii mixed with the stock as previously described for the two inner plies, the two outer plies remaining blank. This sheet was run to 35 caliper and .gave a Mullen. stren h of 60. The content of as halt in the two inner plies was about 70% o the fibre cont nt of these lies. The paper so produced was then subected to the usual tank saturating o eration, passing throu h a tank containing the Mexican asphalt o 110 degrees melting point at approximately 400 degrees F. Onaccount o the great strength of this material, its dryness-and its presaturation, it was possible to pass this through the saturating and coating rollers on a standardroofing machine at the rate of 200 feet a minute, whereasthe maximum speed at which the ordinaryroofing felt of commerce travels during this operation is 105 feet per K111111136. Theresulting saturated sheet was coated after assing through the saturatlng tanks and m e into roofing in the usual manner, the roduct; being a flexible, well-saturated roo g' product containing 140% of asphalt relative to the fibre 0on This specific example is given only as an indication of the possibilities of the process.

' invention as above. described may be being saturated with bitumen may be passed through baths of aqueous liquid such as glue,

casein, zinc chloride, and numerous other liquids such as sulphuric acid, glycerine and particularly those which would' ordinarily pletely disseminated thruout the. plies in the form of a continuous film coating the fibers, outer plies substantially devoid of such binder. intimately unitedto the inner ply or plies, the whole having the characteristics of having had the binder incorporated while dispersed in anaqueous medium and having been rendered sufliciently fluid' to coat the fibers of the inner ply-or plies.

2. A multi-ply sheet having an innerply or plies of bitumen coated fibrous stock and outer plies substantially devoid of bitumen,

having the characteristics of a sheet produced a by the simultaneous formation of fibrous webs, said bitumen extending thruout the inner ply or plies in the form of a continuous film coating the-fibers.

- 3. A process of producing a multi-ply sheet consistingin forming a plurality of webs of. fibrous stock on a multi-cylinder machine, incorporating into the stock forming inner ply or plies a bitumen emulsified while in a liquid condition and combined therewith while in a non-adhesive state, unit- 1 ing the plies while wet and simultaneously dryin the sheet and coalescing the bitumen. 4. .5 process of producing a multi-ply sheet consistingin forming a plurality of webs of fibrous stock on a multi-cylinder machine,

incorporating into the stock forming the in ner plies emulsified bitumen in non-adhesive state, uniting the plies while wet and simultaneously drying the sheet and coalescing the bitumen. '11. 5:1:

5. A processof Q reducing a multi-ply "sheet consisting in fiorming a plurality of webs of 'fibrous s'tock' ona multi-cylinder machine, incorporating-into the stock forming the inner ply emulsified bitumen in non-adhesive state, uniting the' plies while wet and simultaneously dryin the sheet and coalescing the bitumen, an the sheet throu h a saturating liquid. N 6. A'felted E impregnated with a liquid repellant medium, both surfaces offisaid sheet comprising fibrous stock substantial-l devoid of liquid re ellant medium, having't e characteristics of aving had the liquidf're ellant medium while in emulsi' ed condition. LESTER KIRSCHBRAUN.

brous sheet, being interiorly incorporated subsequently passing D 

